Protocol for supporting gateways with redundant routers in a shared domain

ABSTRACT

In an example embodiment, an apparatus with a first interface coupled to a local domain with routers that employ a redundant router protocol, such as Hot Standby Router Protocol (HSRP) and/or Virtual Router Redundancy Protocol (VRRP), and a second interface coupled with a shared domain, such as Virtual Private LAN (Local Area Network) Service (VPLS), and virtual bridging logic coupled with the first and second interfaces. The virtual bridging logic performs packet snooping, filtering and/or provides a proxy service so that the routers employing the redundant router protocol are localized in the local domain, and avoids the routers employing the redundant router protocol from associating with other routers employing the redundant routing protocol that are in another local domain coupled with the shared domain.

TECHNICAL FIELD

The present disclosure relates generally to supporting gateways withredundant routers coupled with a shared domain.

BACKGROUND

Globalization, business process optimization, and the need forcontinuous computing operations motivate business to seek solutions thatcan both distribute and unite data centers over geographically dispersedlocations. Geographically distributed data centers are desirable formutual backup to reduce interruptions from local disasters and also tofacilitate data center maintenance.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated herein and forming a part of thespecification illustrate the example embodiments.

FIG. 1 illustrates an example of a network of a shared domain withgateways that have redundant routers.

FIG. 2 illustrates an example of an apparatus for supporting redundantrouters in a shared domain.

FIG. 3 illustrates an example of an apparatus for supporting redundantrouters in a shared domain with an interface for communicating with alocal domain and an interface for communicating with a shared domain.

FIG. 4 is a block diagram that illustrates a computer system upon whichan example embodiment may be implemented.

FIG. 5 illustrates an example methodology for supporting gateways withredundant routers coupled with a shared domain.

OVERVIEW OF EXAMPLE EMBODIMENTS

The following presents a simplified overview of the example embodimentsin order to provide a basic understanding of some aspects of the exampleembodiments. This overview is not an extensive overview of the exampleembodiments. It is intended to neither identify key or critical elementsof the example embodiments nor delineate the scope of the appendedclaims. Its sole purpose is to present some concepts of the exampleembodiments in a simplified form as a prelude to the more detaileddescription that is presented later.

In accordance with an example embodiment, there is disclosed herein anapparatus with a first interface coupled to a local domain with routersthat employ a redundant router protocol such as Hot Standby RouterProtocol (HSRP) and/or Virtual Router Redundancy Protocol (VRRP), and asecond interface coupled with a shared domain such as Virtual PrivateLAN (Local Area Network) Service (VPLS), and virtual bridging logiccoupled with the first and second interfaces. The virtual bridging logicperforms packet snooping, filtering and/or provides a proxy service sothat the routers employing the redundant router protocol are localizedin the local domain, and avoids the routers employing the redundantrouter protocol from associating with other routers employing theredundant routing protocol that are in another local domain coupled withthe shared domain.

DESCRIPTION OF EXAMPLE EMBODIMENTS

This description provides examples not intended to limit the scope ofthe appended claims. The figures generally indicate the features of theexamples, where it is understood and appreciated that like referencenumerals are used to refer to like elements. Reference in thespecification to “one embodiment” or “an embodiment” or “an exampleembodiment” means that a particular feature, structure, orcharacteristic described is included in at least one embodimentdescribed herein and does not imply that the feature, structure, orcharacteristic is present in all embodiments described herein.

FIG. 1 illustrates an example of a network 100 of a shared domain 102coupled with gateways 110, 114 that employ redundant routers. Forpurposes of illustration, the shared domain 102 in the illustratedexample is a Virtual private LAN (Local Area Network) service (VPLS)network (or VPLS domain), however those skilled in the art shouldreadily appreciate that the principles described herein are applicablewith other types of shared domains. VPLS provides Ethernet basedmultipoint to multipoint communication over IP/MPLS (InternetProtocol/Multiprotocol Label Switching) networks. VPLS allowsgeographically dispersed sites to share an Ethernet broadcast domain byconnecting sites through pseudo-wires (PWs). A Provider Edge (PE) (e.g.,PE's 104, 106, 108) is where the VPLS originates and terminates. The PEsets up the appropriate communications, such as tunnels, to communicatewith other PEs coupled with the VPLS. For example, the exampleillustrated in FIG. 1 has three PEs, a first PE (PE1) 104, a second PE(PE2) 106, and a third PE (PE3) 108. As those skilled in the art shouldreadily appreciate, a VPLS network may employ any physically realizablenumber of PEs, and that the number of PEs selected in FIG. 1 whereselected merely for ease of illustration. Those skilled in the artshould also readily appreciate that the PEs may be geographicallydispersed from each other. For example, PE1 104 may be located in a datacenter in San Jose, Calif., PE2 106 may be located in a data center inCleveland, Ohio, and PE3 108 may be located in a data center in Atlanta,Ga.

In the illustrated example, the first PE (PE1) 104 couples the VPLSdomain 102 with a first local domain (Local Domain 1) that comprises agateway (“HSRP GW1”) 110 that comprises redundant routers employing aredundant routing protocol (HSRP in this example, although theprinciples described herein are also applicable to other redundantrouting protocols such as VRRP). By redundant routers is meant a gatewaythat employs multiple routers for routing packets. A protocol associatedwith the redundant routers controls the operation of the redundantrouters. For example, Hot Standby Routing Protocol (HSRP) is a standard,defined in RFC 2281 (March 1998), that calls for a mirrored router inpassive mode to send hello packets, wait for a lead router to die and,without dropping a packet, take over from that router. Virtual RouterRedundancy Protocol (VRRP) is a protocol defined in RFC 3768 (April2004) for switching to a backup router in the case of failure. Two ormore routers are set up with VRRP, and one is elected the “master.” Themaster router continuously sends advertisement packets to the backups,and if the advertisements stop, one of the backup routers becomes themaster. All routers share a “virtual IP” address, so they are all seenas one address. VRRP can also be used for load sharing. As those skilledin the art can readily appreciate, the principles described herein arenot specific to any one or more redundant router protocols, such as HSRPand/or VRRP, but can be employed with any suitable redundant routerprotocol.

The HSRP GW1 110 is coupled to a first LAN, (LAN1) 112. The second PE106 coupled the VPLS domain 102 with a second local domain (Local Domain2) that comprises a gateway (HSRP GW2) 114 that also comprises redundantrouters. The HSRP GW2 114 is coupled with a second LAN (LAN2) 116. Thethird PE 108 coupled the VPLS domain 102 with a third local domain(Local Domain 3) that comprises a third LAN (LAN3) 118. In theillustrated example, the third LAN 118 does not employ redundant routersthat use a protocol such as HSRP or VRRP. In addition, the third PE 108also functions as the gateway for the third LAN 118, illustrating thatin accordance with an example embodiment, gateways and PEs may also beimplemented by a single device and/or multiple devices.

In an example embodiment, because the first PE 104 and the second PE 106are coupled with gateways having routers that employ a redundant routingprotocol, the first PE 104 and the second PE 106 may restrict certainpackets from the VPLS (shared) domain 102. For example, packets that maybe restricted from the VPLS (shared) domain 102 include but are notlimited to predefined HSRP packets, predefined VRRP packets, GLBP(“Gateway Load Balancing Protocol”—a proprietary protocol available fromCisco Systems, Inc., 170 West Tasman Dr., San Jose, Calif. 95134)packets, and ARP (Address Resolution Protocol) packets.

In an example embodiment, the PEs 104, 106, 108 snoop packets receivedfrom the VPLS domain 102 to determine whether there are other localdomains coupled with the VPLS domain 102 that are employing theredundant routing protocol (HSRP in this example).

In an example embodiment, the first PE 104 and the second PE 106 filterpredefined (e.g., HSRP) packets sent by routers coupled with the HSRPGW1 110 and the HRSP GW2 114 respectively addressed to the VPLS domain102. For example, HSRP Coup and/or Resign message types may be filteredand blocked from entering the VPLS (shared) domain 102.

In an example embodiment, the first PE 104 and the second PE 106 providea proxy service for the routers employing the HSRP (redundant routingprotocol, e.g., the HRSP GW1 110 and the HSRP GW2 114 respectively). Forexample, the proxy service may suitably comprise snooping a packetemployed by the HSRP protocol and changing the priority level to a lowerlevel (e.g., the lowest priority level) before forwarding the packetonto the VPLS domain 102.

In an example embodiment, the first PE 104 and the second PE 106 mayalso snoop and/or filter HSRP packets received from the VPLS domain 102.For example, to prevent a router on another local domain from becomingthe primary router in a local domain, the priority level of routers forpackets received from the VPLS domain 102 may be changed to the lowestlevel.

In the illustrated example, the VPLS domain 102 is associated with avirtual Media Access Control (MAC) address. The first PE 104 and thesecond PE 106 can filter or proxy packets received from the localdomains (e.g., local domain 1 and local domain 2 respectively) that areaddressed to the virtual MAC address.

An aspect of an example embodiment is that a router associated with onelocal domain employing redundant routing protocol can be prevented frombecoming the default router for another local domain employing theredundant routing protocol. For example, if a router at HSRP GW2 114became the active router for both the HSRP GW1 110 and the HSRP GW2 114,then traffic from a devices associated with the LAN1 112 would be routedacross the VPLS domain 102 to the HRSP GW2 114 for forwarding. Forexample, if the LAN1 112 is located in the United States and the LAN 2116 is located in Europe, if a router on the HSRP GW2 114 becomes theactive router for the Local Domain 1, then traffic from a deviceassociated with the LAN 1 112 (in the United States) would be routedacross the VPLS domain 102 to the HRSP GW2 114 (in Europe) forforwarding, which could result in delay and unnecessary consumption ofbandwidth on the VPLS domain 102. Thus, because the example embodimentsdescribed herein localize (or isolate) routers employing a redundantrouting protocol on different domains, the example embodiments describedherein can be said to support an Active/Active gateway scenario.

FIG. 2 illustrates an example of an apparatus 200 for supportingredundant routers in a shared domain. The apparatus 100 is suitable forimplementing the functionality of the first PE 104, the second PE 106,and the third PE 108 described herein in FIG. 1.

The Apparatus 200 comprises virtual bridging (VB) logic 202 for couplinga local domain with a shared domain. “Logic”, as used herein, includesbut is not limited to hardware, firmware, software stored in anon-transient medium, and/or combinations of each to perform afunction(s) or an action(s), and/or to cause a function or action fromanother component. For example, based on a desired application or need,logic may include a software controlled microprocessor, discrete logicsuch as an application specific integrated circuit (“ASIC”), system on achip (“SoC”), programmable system on a chip (“PSOC”), aprogrammable/programmed logic device, a non-transient memory devicecontaining instructions, or the like, or combinational logic embodied inhardware. Logic may also be fully embodied as software stored on anon-transitory, tangible medium which performs a described function whenexecuted by a processor. Logic may suitably comprise one or more modulesstored on a non-transitory tangible medium configured to perform one ormore functions.

In an example embodiment, the shared domain is a logically shareddomain. For example, the shared domain may be a VPLS domain.

In an example embodiment, a gateway comprising redundant routersemploying a redundant routing protocol are coupled with the localdomain. The redundant routing protocol may be any suitable protocol,such as HSRP and/or VRRP.

In an example embodiment, the virtual bridging logic 202 is operable tosnoop packets received from the shared domain. The virtual bridginglogic 202 may snoop the packets received from the shared domain todetermine whether another (e.g., second) local domain that is coupledwith the shared domain is employing the redundant routing protocol. Inparticular embodiments, the virtual bridging logic 202 may filterredundant routing protocol packets received from the shared domainand/or modify the packets, such as for example, changing the prioritylevel of redundant routing protocol packets received from the shareddomain.

In an example embodiment, the virtual bridging logic 202 filtersredundant routing protocol packets received on the local domain that areaddressed to the shared domain. For example, if the shared domain is alogically shared domain such as a VPLS domain identified by a virtualMAC address, packets received on the local interface addressed to thevirtual MAC address are filtered.

In an example embodiment, the virtual bridging logic 202 is operable toprovide a proxy service for the routers employing the redundant routingprotocol coupled with the local domain. The proxy service may suitablycomprise snooping a packet employed by the redundant routing protocol,the packet having a priority level. The virtual bridging logic 202changes the priority level to a lower (e.g. the lowest) priority levelbefore routing the packet onto the shared domain. In particularembodiments, the proxy service may also be employed to change thepriority level of packets received from the shared domain beforeforwarding onto the local domain.

FIG. 3 illustrates an example of an apparatus 300 for supportingredundant routers in a shared domain. For example, the apparatus 300 issuitable for implementing the functionality of the first PE 104, thesecond PE 106, and the third PE 108 described herein in FIG. 1. Theapparatus 300 comprises virtual bridging logic 202 that employs a firstinterface 302 to communicate with the local domain and a secondinterface 304 to communicate with the shared domain.

In an example embodiment, the shared domain is a logically shareddomain. For example, the shared domain may be a VPLS domain.

In an example embodiment, a gateway comprising redundant routersemploying a redundant routing protocol are coupled with the localdomain. The redundant routing protocol may be any suitable protocol suchas HSRP and/or VRRP.

In an example embodiment, the virtual bridging logic 202 is operable tosnoop packets received from the shared domain via the second interface304. The virtual bridging logic 202 may snoop the packets received fromthe shared domain to determine whether another (e.g., second) localdomain that is coupled with the shared domain is employing the redundantrouting protocol. In particular embodiments, the virtual bridging logic202 may filter redundant routing protocol packets received from theshared domain and/or modify the packets, such as for example, changingthe priority level of redundant routing protocol packets received fromthe shared domain.

In an example embodiment, the virtual bridging logic 202 filtersredundant routing protocol packets received from the local domain on thefirst interface 302 that are addressed to the shared domain. Forexample, if the shared domain is a logically shared domain such as aVPLS domain identified by a virtual MAC address, packets received on thelocal interface addressed to the virtual MAC address are filtered.

In an example embodiment, the virtual bridging logic 202 is operable toprovide a proxy service for the routers employing the redundant routingprotocol coupled with the local domain coupled with the first interface302. The proxy service may suitably comprise snooping a packet employedby the redundant routing protocol, the packet having a priority level.The virtual bridging logic 202 changes the priority level to a lower(e.g., the lowest) priority level before routing the packet onto theshared domain via the second interface 304. In particular embodiments,the proxy service may also be employed to change the priority level ofpackets received from the shared domain before forwarding onto the localdomain.

FIG. 4 is a block diagram that illustrates a computer system 400 uponwhich an example embodiment may be implemented. The computer system 400includes a bus 402 or other communication mechanism for communicatinginformation and a processor 404 coupled with the bus 402 for processinginformation. The computer system 400 also includes a main memory 406,such as random access memory (RAM) or other dynamic storage devicecoupled to the bus 402 for storing information and instructions to beexecuted by the processor 404. The main memory 406 also may be used forstoring a temporary variable or other intermediate information duringexecution of instructions to be executed by the processor 404. Thecomputer system 400 further includes a read only memory (ROM) 408 orother static storage device coupled to the bus 402 for storing staticinformation and instructions for the processor 404. A storage device410, such as a magnetic disk, optical disk, and/or flash storage, isprovided and coupled to the bus 402 for storing information andinstructions.

An aspect of the example embodiment is related to the use of thecomputer system 400 for implementing a protocol for supporting gatewayswith redundant routers coupled with a shared domain. According to anexample embodiment, implementing a protocol for supporting gateways withredundant routers coupled with a shared domain is provided by thecomputer system 400 in response to the processor 404 executing one ormore sequences of one or more instructions contained in the main memory406. Such instructions may be read into the main memory 406 from anothercomputer-readable medium, such as the storage device 410. Execution ofthe sequence of instructions contained in the main memory 406 causes theprocessor 404 to perform the process steps described herein. One or moreprocessors in a multi-processing arrangement may also be employed toexecute the sequences of instructions contained in the main memory 406.In alternative embodiments, hard-wired circuitry may be used in place ofor in combination with software instructions to implement an exampleembodiment. Thus, the example embodiments described herein are notlimited to any specific combination of hardware circuitry and software.

The term “computer-readable medium” as used herein refers to any mediumthat participates in providing instructions to the processor 404 forexecution. Such a medium may take many forms, including but not limitedto non-volatile media, and volatile media. Non-volatile media include,for example, optical or magnetic disks, such as storage device 410.Volatile media include dynamic memory such as main memory 406. As usedherein, tangible media may include volatile and non-volatile media.Common forms of computer-readable media include, for example, floppydisk, a flexible disk, hard disk, magnetic cards, paper tape, any otherphysical medium with patterns of holes, a RAM, a PROM, an EPROM, aFLASHPROM, CD, DVD or any other memory chip or cartridge, or any othermedium from which a computer can read.

Various forms of computer-readable media may be involved in carrying oneor more sequences of one or more instructions to the processor 404 forexecution. For example, the instructions may initially be borne on amagnetic disk of a remote computer. The remote computer can load theinstructions into its dynamic memory and send the instructions over atelephone line using a modem. A modem local to the computer system 400can receive the data on the telephone line and use an infraredtransmitter to convert the data to an infrared signal. An infrareddetector coupled to the bus 402 can receive the data carried in theinfrared signal and place the data on the bus 402. The bus 402 carriesthe data to the main memory 406 from which the processor 404 retrievesand executes the instructions. The instructions received by the mainmemory 406 may optionally be stored on the storage device 410 eitherbefore or after execution by the processor 404.

The computer system 400 also includes a first communication interface418 coupled to the bus 402. The first communication interface 418provides two-way data communication coupling the computer system 400 toa network link 420 that is coupled with a local network (domain) 422.The computer system 400 further comprises a second communicationinterface 424 coupled to the bus 402. The second communication interface424 is coupled to a network link 426 that is coupled with a shared (VPLSin this example) network (or domain) 428. The second communicationinterface 424 provides bidirectional communications with the VPLSnetwork 428.

In operation, the processor 404 determines whether packets received fromthe local network 422 via the network link 420 and the communicationinterface 418 should be forwarded onto the VPLS network 428 via thecommunication interface 424 and the network link 426. Similarly, theprocessor 404 determines whether packets received from the VPLS network428 via the communication interface 424 and the network link 426 shouldbe forwarded onto the network 422 via the network link 420 and thecommunication interface 418. For example, the processor 404 may filtercontrol plane and data plane packets received from a redundant routerassociated with a gateway coupled with the local network 422.

In view of the foregoing structural and functional features describedabove, a methodology 500 in accordance with an example embodiment willbe better appreciated with reference to FIG. 5. While, for purposes ofsimplicity of explanation, the methodology 500 of FIG. 5 is shown anddescribed as executing serially, it is to be understood and appreciatedthat the example embodiment is not limited by the illustrated order, assome aspects could occur in different orders and/or concurrently withother aspects from that shown and described herein. Moreover, not all ofthe illustrated features may be required to implement a methodology inaccordance with an aspect of an example embodiment. The methodology 500described herein is suitably adapted to be implemented in hardware,software, or a combination thereof.

At 502, a determination is made whether one or more gateways employingredundant routers are coupled with a local domain. Data representativeof gateways employing redundant routers may be forwarded onto a shared(e.g., logically shared) domain such as a VPLS domain. For example, if agateway with redundant routers is detected in the local domain, datarepresentative of the gateway with redundant routers is transmitted ontothe shared domain. In addition, data representative of gateways fromother local domains that have routers employing a redundant routingprotocol (such as HSRP and/or VRRP) that are coupled with the shareddomain may be received from the shared domain.

At 504, predefined redundant routing protocol packets received from thelocal domain addressed to the shared domain are filtered. For example,if the shared domain is a VPLS domain with a virtual MAC address,predefined packets received from the local domain addressed to thevirtual MAC address are filtered.

At 506, a proxy service is provided for redundant routing protocolpackets received from a local domain that are addressed to the shareddomain. The proxy service may suitably comprise changing the prioritylevel of the packet to a lower (e.g., the lowest) priority level beforerouting the packet onto the shared domain.

Described above are example embodiments. It is, of course, not possibleto describe every conceivable combination of components ormethodologies, but one of ordinary skill in the art will recognize thatmany further combinations and permutations of the example embodimentsare possible. Accordingly, this application is intended to embrace allsuch alterations, modifications and variations that fall within thespirit and scope of the appended claims interpreted in accordance withthe breadth to which they are fairly, legally and equitably entitled.

The invention claimed is:
 1. An apparatus to restrict bandwidthconsumption in a shared domain when the shared domain operativelyconnects multiple local domains employing the same redundant routingprotocol, the apparatus comprising: one or more computer processorsoperatively connected to a memory; a first network interface deviceconnecting the apparatus to a first of the multiple local domains, thefirst local domain having a first set of one or more routers employing aredundant routing protocol; a second network interface device connectingthe apparatus to the shared domain; and virtual bridging logicoperatively connected to the first network interface device and thesecond network interface device, respectively, the virtual bridginglogic executable by the one or more computer processors to perform anoperation to reduce bandwidth consumption in the shared domain bypreventing any given router in the first local domain from becoming anactive router for the second local domain based on a priority level ofpackets employing the redundant routing protocol, the operationcomprising: snooping ingress packets received via the second networkinterface device to determine whether a second of the multiple localdomains, operatively connected to the shared domain and including asecond set of one or more routers, is employing the redundant routingprotocol; determining that the second local domain is employing theredundant routing protocol; subsequent to a first router of the firstset of one or more routers becoming an active router for the first localdomain based on the priority level of packets employing the redundantrouting protocol, providing a proxy service for the first set of one ormore routers; snooping an egress packet employed by the redundantrouting protocol, the packet having a first priority level and beingcommunicated from the first set of one or more routers of the firstlocal domain to the second set of one or more routers of the secondlocal domain; and responsive to determining that the second local domainis employing the redundant routing protocol, selectively changing thefirst priority level of the egress packet to a second priority levellower than the first priority level before routing the egress packetrelative to the first local domain.
 2. The apparatus of claim 1, whereinthe shared domain is associated with a virtual media access control(MAC) address.
 3. The apparatus of claim 1, wherein preventing any givenrouter from becoming an active router for the second local domaincomprises filtering predefined packets sent by the router on first localdomain employing the redundant routing protocol and addressed to theshared domain, wherein the filtering comprises filtering packetsreceived on the first network interface device that are associated withthe redundant routing protocol and that are addressed to the virtualmedia access control (MAC) address.
 4. The apparatus of claim 1, whereinthe redundant routing protocol is a Hot Standby Router Protocol.
 5. Theapparatus of claim 1, wherein the redundant routing protocol is aVirtual Router Redundancy Protocol.
 6. A non-transitorycomputer-readable medium containing a program executable to perform anoperation to restrict bandwidth consumption in a shared domain when theshared domain operatively connects multiple local domains employing thesame redundant routing protocol, the operation comprising: by one ormore computer processors when executing the program, performing a firstoperation to reduce bandwidth consumption in the shared domain bypreventing any given router in a first of the multiple local domainsfrom becoming an active router for a second of the multiple localdomains based on a priority level of packets employing a redundantrouting protocol, the first local domain having a first set of one ormore redundant routers that employ the redundant routing protocol, thesecond local domain including a second set of one or more routers, thefirst operation comprising: perform virtual bridging between the firstlocal domain and the shared domain; snooping ingress packets todetermine whether the second local domain is employing the redundantrouting protocol; determining that the second local domain is employingthe redundant routing protocol; subsequent to a first router of thefirst set of one or more routers becoming an active router for the firstlocal domain based on the priority level of packets employing theredundant routing protocol, providing a proxy service for the first setof one or more routers; snooping an egress packet employed by theredundant routing protocol, the packet having a first priority level andbeing communicated from the first set of one or more redundant routersof the first local domain to the second set of one or more routers ofthe second local domain; and responsive to determining that the secondlocal domain is employing the redundant routing protocol, selectivelychanging the first priority level of the egress packet to a secondpriority level lower than the first priority level before routing theegress packet relative to the first local domain.
 7. The non-transitorycomputer-readable medium of claim 6, wherein the shared domain isassociated with a virtual media access control (MAC) address.
 8. Thenon-transitory computer-readable medium of claim 7, wherein preventingany given router from becoming an active router for the second localdomain comprises filtering predefined packets sent by the router onfirst local domain employing the redundant routing protocol andaddressed to the shared domain, wherein the filtering comprisesfiltering packets sent from the local domain that are associated withthe redundant routing protocol and that are addressed to the virtualmedia access control (MAC) address.
 9. The non-transitorycomputer-readable medium of claim 6, wherein the redundant routingprotocol is a Hot Standby Router Protocol.
 10. The non-transitorycomputer-readable medium of claim 6, wherein the redundant routingprotocol is a Virtual Router Redundancy Protocol.
 11. Acomputer-implemented method to restrict bandwidth consumption in ashared domain when the shared domain operatively connects multiple localdomains employing the same redundant routing protocol, thecomputer-implemented method comprising: by one or more computerprocessors, performing an operation to reduce bandwidth consumption inthe shared domain by preventing any given router in the first localdomain from becoming an active router for the second local domain basedon a priority level of packets employing the redundant routing protocol,the operation comprising: obtaining first data associated with a firstset of one or more routers in a first of the multiple local domainsoperatively connected via the shared domain; obtaining second dataassociated with a second set of one or more routers in a second of themultiple local domains; determining that the first data isrepresentative of the first set of one or more routers employing aredundant routing protocol in the first local domain; determining thatthe second data is representative of the second set of one or morerouters employing the redundant routing protocol in the second localdomain; subsequent to a first router of the first set of one or morerouters becoming an active router for the first local domain based onthe priority level of packets employing the redundant routing protocol,providing a proxy service for the first set of one or more routers;snooping an egress packet employed by the redundant routing protocol,the packet having a first priority level and being communicated from thefirst set of one or more routers of the first local domain to the secondset of one or more routers of the second local domain; and responsive todetermining that the second data is representative of the second set ofone or more routers employing the redundant routing protocol in thesecond local domain, selectively changing the first priority level ofthe egress packet to a second priority level lower than the firstpriority level before routing the egress packet relative to the firstlocal domain.
 12. The computer-implemented method of claim 11, whereinthe shared domain is associated with a virtual media access control(MAC) address.
 13. The computer-implemented method of claim 11, whereinpreventing any given router from becoming an active router for thesecond local domain comprises filtering predefined packets sent by therouter on first local domain employing the redundant routing protocoland addressed to the shared domain, wherein the filtering comprisesfiltering packets received on the first local domain that are addressedto the virtual media access control (MAC) address.
 14. Thecomputer-implemented method of claim 11, wherein the redundant routingprotocol is one of a group consisting of a Hot Standby Router Protocoland a Virtual Router Redundancy Protocol.
 15. The computer-implementedmethod of claim 11, wherein preventing any given router from becoming anactive router for the second local domain comprises preventing any givenrouter from becoming an active router for the second local domain as aresult of the first and second local domains employing the sameredundant routing protocol, wherein reducing bandwidth consumption inthe shared domain comprises preventing, based on any given routerprevented from becoming an active router for the second local domain,network traffic from being forwarded through the shared domain for theactive router to then forward.
 16. The computer-implemented method ofclaim 15, wherein preventing any given router from becoming an activerouter for the second local domain comprises filtering predefinedpackets sent by the router on first local domain employing the redundantrouting protocol and addressed to the shared domain, wherein theredundant routing protocol comprises, in respective instances: (i) HotStandby Router Protocol (HSRP) and (ii) Virtual Router RedundancyProtocol (VRRP); wherein the predefined packets include, in respectiveinstances: (i) a HSRP Coup message; (ii) a HSRP Resign message; (iii) aVRRP message; (iv) a Gateway Load Balancing Protocol (GLBP) message; and(v) an Address Resolution Protocol (ARP) message.
 17. Thecomputer-implemented method of claim 16, wherein the shared domaincomprises a virtual private local area network (LAN) service (VPLS)domain, wherein the VPLS domain has a virtual media access control (MAC)address, wherein the VPLS domain provides Ethernet-based,multipoint-to-multipoint communication over one or more InternetProtocol/Multiprotocol Label Switching (IP/MPLS) networks.
 18. Thecomputer-implemented method of claim 17, wherein the proxy service isprovided by a provider edge router, wherein the provider edge router isoperatively connected to the first set of one or more routers in thefirst local domain via a first network interface, wherein the provideredge router is operatively connected to the shared domain via a secondnetwork interface.
 19. The computer-implemented method of claim 18,wherein the first network interface is operatively connected to thesecond network interface via virtual bridging logic, wherein the virtualbridging logic snoops packets received via the second network interfacedevice in order to determine that the first and second local domainsemploy the same redundant routing protocol, wherein the proxy service isprovided by the virtual bridging logic.
 20. The computer-implementedmethod of claim 19, wherein the predefined packets are filtered by thevirtual bridging logic, wherein filtering the predefined packetscomprises filtering packets received on the first network interface thatare associated with the redundant routing protocol and addressed to thevirtual MAC address.